Hallo Satish,

such a circuit can easily be implemented. Have a look:




For achieving satisfying performance some design rules have to be obeyed:

1. R1 and R3 should be about 1000 times greater than shunt resistance.

2. Circuit will only show adequate common mode rejection if voltage at both inputs is divided by exactly the same factor. Means, R1 / R3 = R2 x (1 / R4 + 1 / R5)!!
Any mismatch will drastically worsen common mode rejection ratio. So, the use of 0.1% precision types for R1...R5 is highly recommended. If resistors show maximum errors, 'only' about 45dB CMRR can be achieved! That's enough for most purposes, but a 'universe' worse than RCV420.

3. Circuit can accept up to +-40V at inputs. So, very high common mode voltages can be handled.

4. Gain MUST NOT be adjusted with resistors R1...R5, otherwise CMRR will drastically suffer. So, an additional stage with gain is necessary for producing 0...5V span.

5. Circuit has the advantage, that both calibrations do not influence each other, means once offset is adjusted, gain calibration will not influence offset setting: Apply 4mA and adjust with offset trimmer for 0V at output. Then apply 20mA and adjust with gain trimmer for 5.0V at output.

6. Of course, at input stage operational amplifier with low offset voltage and low input bias current must be used. A Fet-OPamp like TL051 is a good choice.

7. Keep in mind, that this is a simplified schematic, not showing any filtering and protection measures!

Kai